Various surgical instruments and methods have been devised for the implantation of devices into the disc space between adjacent vertebrae of the spinal column. For example, spinal fusion procedures can require sequential distraction to restore the disc space height prior to inserting a pair of fusion devices in the disc space in side-by-side relation. To implant these devices, an initial opening or openings are made in the disc space at the locations through which the devices are to be inserted. A first distractor is inserted in the disc space at one of the device locations. A second larger distractor is inserted in the disc space at the other of the device locations. Sequential distraction in alternate disc space locations is continued until the desired disc space height is achieved. The next to last inserted distractor is then removed. The disc space is prepared for insertion of one fusion device in the location previously occupied by the withdrawn distractor while the other distractor maintains the restored disc space height.
In another technique, a spinal disc space is accessed and distracted for insertion of an implant. Distraction of the disc space is maintained by applying a distraction force to bone screws engaged in the vertebrae on each side of the disc space.
While the above procedure can be effective for some techniques, there are disadvantages. For example, dissection and retraction of tissue, vasculature and nervature is required to accommodate the pair of distractors inserted in the disc space, or to accommodate the external distractors. Alternating sequential distraction can be time-consuming and requires many steps to complete the surgical procedure. Engagement of bone screws to the vertebrae and application of a distraction force to the engaged bone screws also requires additional time and steps in the surgical procedure.
There remains a need for instruments and techniques for restoring and maintaining a spinal disc space anatomy that minimizes dissection and retraction and of tissue, vasculature and nervature. There further remains a need for instruments and techniques for restoring and maintaining a spinal disc space anatomy that minimizes the steps and complexity of the procedure during surgery.